THE  PREPARATION  AND  REACTIONS  OF 
PARACHLOROPHENYLARSINE 

BY 


WALLACE  HUME  CAROTHERS 
B.  S.  Tarkio  College 
1920 


THESIS 

Submitted  in  Partial  Fulfillment 
of  the  requirements  for  the 
Degree  of 

MASTER  OF  SCIENCE 
IN  CHEMISTRY 

IN 

THE  GRADUATE  SCHOOL 

OF  THE 

UNIVERSITY  OF  ILLINOIS 


1921 


Digitized  by  the  Internet  Archive 

in  2016 


https://archive.org/details/preparationreactOOcaro 


UNIVERSITY  OF  ILLINOIS 


THE  GRADUATE  SCHOOL 


x r 


192 


% 


I HEREBY  RECOMMEND  THAT  THE  THESIS  PREPARED  UNDER  MY 
SUPERVISION  BY Wallace  H.  Caro  there 

ENTITLED  .The  Preparation  and  Reactions  of  p-Chlorophenylarsine 


BE  ACCEPTED  AS  FULFILLING  THIS  PART  OF  THE  REQUIREMENTS  FOR 
THE  DEGREE  OF Master  of  Science 


IaC  J)- 


In  Charge  of  Thesis 


Head  of  Department 


Recommendation  concurred  in* 


Committee 

on 

Final  Examination* 


^Required  for  doctor’s  degree  but  not  for  master’s 


...V,  -•  • • 


. 


. 


'll  ASIA  OF  COiS'i'iiil'Ji’S 


THJSORRTICAL  AM)  HISTORICAL  I 

DESCRIPTIVE  4 

SIGHIFICAHCE  OF  RESULTS  12 

MPRRIMiSHTAL  16 

Preparation  & properties  of  p-ehlorophenylarsonic  acid  16 

Preparation  and  properties  of  p-chlorophenylarsine  £0 

Analysis  of  p-chlorophenylarsine-benjzaldehyde  product  £6 

Analysis  of  p-chlorophenylarsine -paraldehyde  product  £7 

Preparation  of  arsanilic  acid  and  its  reduction  £b 

Preparation  of  p-phenoiarsonic  acid  and  its  reduction  £1 

Preparation  of  p- phene tylarsonic  acid  and  its  reduction  £4 

SUMMARY  35 

ACKHOWnCilXJisiMJiRT  36 


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1 


THE  PREPARATION  AND  REACTIONS  OF  P AR A CH LOR OPIIENYL ARSINE. 

I.  THEORETICAL  AND  HISTORICAL. 

Arsenic  occurs  in  the  periodic  table  in  the  fifth  vertical 
column  below  phosphorous  which  stands  just  under  nitrogen,  a fnct 
which  would  lead  to  the  prediction  that  arsenic  and  nitrogen  would 
show  some  similarities.  Physically  they  are,  of  course,  quite  dif- 
ferent, but  chemically  their  properties  bear  out  this  prediction 
in  many  respects.  Thus,  both  elements  form  stable  hydrides  in 

which  the  element  is  trivalent;  both  form  stable  oxides  in  which 

1  2 

the  element  is  either  tri-  or  pentavalent;  both  form  halides  \ 
Similar  analogies  exist  in  the  formation  of  organic  deriva- 
tives and  in  the  chemical  properties  of  these  derivatives.  The 
hydrides  of  both  elements  yield  derivatives  in  which  one  hydrogen 
is  replaced  by  an  alkyl  or  aryl  group,  the  primary  amines  being 
thus  derived  from  ammonia,  and  the  primary  organic  arsines  from 

arsine.  Amines  were  predicted  to  be  capable  of  existence  by 

3 4 

Liebig  in  1842  , were  first  prepared  by  Wurtz  , and  since  then 

have  been  extensively  studied  and  have  been  found  to  be  of  enormous 
importance  in  organic  chemistry,  the  aromatic  amine  compounds  be- 
ing especially  important  in  the  synthesis  of  other  compounds  of 
many  diverse  types. 

The  existence  of  primary  organic  arsines  would  of  course,  be 

predicted  by  analogy,  but  attempts  to  prepare  compounds  of  this 
5 

type  failed  until  A.  W.  Palmer  succeeded  in  reducing  methyl  and 

1 Wm.  H.  Dehn  Amer.  Chem.  Journ.  33,  101  (1905) 

2 Gilbert  T.  Morgan,  Organic  compounds  of  Arsenic  and  antimony,  xi. 

3 Handworterbuch,  1,  689. 

4 Ann.  Cham.  (Liebig)  71,  330,  76,  318. 

5 Ann.  Chem.,  107,  285. 


. 

■ . 
.. 


* 


. ‘ 


2. 

0 

phenyl  arsenic  acids  and  isolating  the  corresponding  arsines.' 

It  then  appeared  that  the  failure  of  previous  investigators  had 

been  due  to  the  absence  of  precautions  to  protect  the  product  from 

the  air;  primary  arsines  being  oxidized  instantaneously.  Since 

then  several  other  primary  arsines,  both  aromatic  and  aliphatic 

7 

have  been  prepared  , and  there  is  no  apparent  theoretical  reason 
why  the  list  should  not  be  extended  indefinitely. 

The  properties  of  primary  arsines  have  been  studied  most  ex- 

Q 

tensive ly  by  Dehn  . He  found  that  like  the  primary  amines  they 
react  readily  with  alkyl  halides  with  the  formation  of  secondary 
and  tertiary  arsines  and  quarternary  arsonium  compounds,  that,  they 
are  formed  by  the  reduction  in  acid  solution  of  any  monoarylated 
or  monoalkylated  arsenic  compound,  that  in  certain  cases  they  com- 
bine with  sulphuric  acid  with  the  formation  of  unstable  salts. 

On  the  other  hand  the  primary  arsines  are  oxidized  much  more  read- 
ily than  are  the  amines,  halogens  readily  replace  the  hydrogen 
attached  to  the  arsenic,  etc.,  showing  the  effect  of  the  more  pos- 
itive character  of  the  arsenic  atom. 

Phenyl  arsine  is  the  structural  analogue  of  aniline,  and  as 
may  be  seen  from  a comparison  of  the  formulas  of  the  two  compounds 
the  formal  resemblance  is  very  close,  especially  when  the  proximity 
of  nitrogen  and  arsenic  in  the  periodic  table  is  taken  into  con- 
sideration. 

6 Ber.  d.  Chem.  Ges.  34,  3594. 

7 Ber.  (1901)  34,  3594. 

Amer.  Chem.  Tourn.  (1908)  40,  113. 

D.  R.  P.  269,  843;  269,  74^7  251,  571;  275,  216; 

Chem.  Abs.  11,  3256. 

8 Am.  Chem.  Journ.,  33,  101;  40,  88;  35,  1 (1906) 


. 


. 


' 


3 


To  what  extent  this  structural  analogy  finds  its  outward  ex- 
pression in  chemical  properties  has  been  indicated  above  for  cer- 
tain reactions.  But  there  are  other  reactions  in  which  these 
similarities  might  be  expected  to  manifest  themselves.  Thus, 
aniline  condenses  with  certain  aldehydes  according  to  the  follow- 
ing scheme^: 


Phenyl  arsine  might  be  predicted  to  react  in  a similar  manner: 


This  reaction  has  been  studied  by  Adams  and  Palmer  who 
found  that  no  reaction  takes  place  until  a drop  of  Hcl  is  added. 

A vigorous  reaction  then  sets  in.  The  reaction  instead  of  follow- 
ing the  above  course,  went  as  follows: 


The  product  is  thus  a new  type  of  organic  arsenic  compound. 
This  result  is  of  considerable  importance  for  two  reasons.  In  the 
first  place,  the  existence  of  such  a type  is  of  theoretical  int- 
erest; in  the  second  place,  the  most  promising  field  for  researches 
in  which  the  purpose  to  discover  superior  compounds  to  replace 
arsphenamine  and  neo-ars phenamine,  is  in  the  study  of  new  types  of 
organic  arsenic  compounds11.  Old  types  have  been  pretty  carefully 
studied,  and  the  chief  objection  to  those  which  have  so  far  proved 
most  successful  in  the  treatment  of  syphilis  and  virulent  skin 
diseases  is  instability,  a defect  which  seems  to  be  inherent  in 
the  type  (the  arseno  grouping)  and  which  is  fatally  retained  thru 

9 Vide  L.  Rugheimer,  Ber.  d.  Chera.  Ges.,  39,  1653  (1906) 

10  Journ.  Am.  Chem.  Soc.,  42,  2375  (1920).  The  structure  of 
these  compounds  has  never  been  definitely  proved. 

11  Vide  ibid. 


0 


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0 


^ H n.0 


10 


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■ 


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■ 

* 


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. 


all  th6  enormous  aeries  of  derivatives  of  this  type  which  have 
been  studied. 

The  purpose  of  the  present  investigation  was  to  stuuy  tne 
properties  of  certain  analogues  of  phenyl  arsine  and  their  re- 
actions, especially  the  reaction  with  aldehydes.  The  character 
of  the  reaction  product  between  primary  amines  and  aldehydes  de- 
pends upon  the  character  of  the  aldehyde,  and  aiso  upon  the  na- 

y 

ture  of  the  substituent  in  the  ring  of  the  amino  compound.  It 
should  be  of  interest  to  determine  if  similar  effects  are  opera- 
tive in  the  case  oi  the  arsines. 


i 


8. 


% arsenic 


Caloul  ted  for  CH^O gJI/! AsH-  { OgHgCHO  )2 


19  « 71 


.150?  gran  of  aubatanoe  red.oed  8*03  o.o.  of 

iodine  solution  (1  c .o.»#005515  . arsenic  ) 18.7.3 


.1391  gram  of  eubatance  reduced  7.45  c.c.  o*  io- 
dine solution 


18.8.: 


The  above  product  evidently  Wa3  a condensation  of  one  mole 


of  o-fcolylaraine  and  two  moles  of  onzaldohyde.  The  following  for- 
mula: 


ia  a possible  and  probable  one.  This  condensation  product  is  hytoo- 
lyced  by  cold,  concentrated,  hydrochloric  acid  and  slightly  by  boil- 
ing dilute  hydrochloric.  It  is  not  hydrolyse  by  boiling  five  min- 
utes with  30%  so&iur  hydroxide  solution. 

o-Tolyl  Arsine  and  ar aldehyde. 

A similar  experiment  was  carried  out  to  determine  the  action  of 
paraldehyde  on  o-tol  larsine.  To  about  25  grams  of  the  arsine  a few 
drops  of  concentrated  hydrochloric  acid  and  about  35  prams  of  par al- 
dehyde were  added.  The  mixture  became  slightly  r.rr;.  but  not  so  warm 

A 

as  in  the  previous  experiment • When  the  reaction  had  ceased,  the 
flash  was  sealed  and  set  aside.  After  a few  days  the  r ixture  con- 
taine  a white  solid  and  w,-.s  rather  turbid.  The  excess  paraldehyde , 
about  18  *rmm  >w;...a  distilled  off  at  180  nr.  pressure,  ieavi  p a clear 
yellov7  solution.  An  after .pt  was  made  to  distill  this  at  the  same 
pressure,  but  it  decompose a,  turning  red.  At  23  mm*  it  boiled  at 
165°.  n second  distillation,  about  18  ;rars  of  product,  all rhtly 


u 


3 


— ■ T-r ===== 

turbi J , was  obtained.  In  neither  case  .v  is  .11  ox  the  product  dis- 
tilled, as  it  charred  slightly  on  gettiri"  to  a low  volur.c.  m ol.uB- 
i nr  a few  days  a white  solid  settled  out.  The  11  uid  was  accented 
from  the  solid  and  or,  distillation,  a clear  product,  boiling  at 

165°.21rnnu , was  obtained*  The  index  of  refraction  la 
30 

(n)  1.5573  $ aroenic 

Calculated  for  C%C6H4AaHg( CH?CH0)2  29.25 

.0974  -ran  substance  reduced  7.67  c.c.  of 

iodine  solution  ( lo .c .-*003528  *rai  ar- 
senic) 27.78 

.1527  or am  substance  reduced  12.04  c.o. 

Iodine  solution  27.82 

This  substance  po-tcibly  • as  t o structure*. 

H 


JH 

3ir.il ar  to  the  one  suggested  for  the  condensation  product  of  bensal- 
dohyde  and  o-tol;  l.roine. 

The  p .raldohyde  condensation  gro&not  mentioned  above  was  hy- 
drolyzed by  cold,  eoncentraod  hydrochloric  acid,  giving  a strong 
odor  of  paraldehyde  -nd  yellow  and  red  solids.  These  li.  ely  were 
oxidation  products  of  the  o-tolylsraine  which  was  foxed  by  the  hy- 
drolysis. Boiling  dilute  hydrochloric  hydrolyses  the  condensation 
product  slightly.  It  is  not  hydrolysed  with  boiling  dilute  or  cold 
30  .alkali,  but  on  boiling  with  30f  sodium  hydros *de,  it  is  hydro- 
lysed# 


II.  DifiSCKIPTIVii; 


a . 

p-Uhlorophenyiarsine  does  not  appear  in  tne  literature.  J?'or 
the  present  investigation  it  was  prepared  by  a method  similar  to 
that  described  in  1).  K.  P.  £5i,o7x  ±C'~J . Its  pxeparatxon  ana  prop- 
erties are  aesenbed  in  aetail  in  the  experimental  part  oi  this 
paper . 

i'ne  condensation  of  p-chiorophenyiarsme  with  benzaldehyde 
was  carried  out  as  ionows  : ‘i‘o  one  more  oi'  the  pure  redistilled 

arsine  a little  over  two  mores  oi‘  tne  aldehyde  were  added,  tre  n a 
lew  drops  oi  cone.  liCi  solution.  The  mixture  immediately  became 
hot,  an  a completely  solidified  within  a half'  an  hour  to  a whife  , 
amorphous  solid.  The  reactioxi  mixture  was,  oi  course,  kept  in  an 
atmospnere  of  CO  . On  standing  for  an  nour  xii  an  atmospnere  of 
CO  , the  mass  gradually  began  to  turn  yeliow  and  at  one  ena  ui 
i,nx«&  «ji  lour  nours  iu  was  xound  to  nave  changed  completely  to  a 
canary  yeixow.  This  material  was  partiaiiy  soluble  in  hot  chloro- 
benzene. It  was  extracted  with  hot  chlorobenzene,  and  the  hot 
extract  filtered.  On  cooling  the  riitrate,  long  silky  needles 
separated  which  gradually  aggregated  to  cottony  masses  which  seem- 
ed to  render  the  solution  almost  a soxid  mass.  These  cr^s-ais  , vn 
filtering  off  the  liquid  were  found  to  oe  very  light,  the  yield 
from  £0  grams  of  the  arsine  never  amounting  to  over  three  grams 
and  often  failing  beiow  O.n  &ram.  They  were  recrystarlized  se  verai 
times  from  a mixture  of  chlorobenzene  and  alcohol.  The  results 
were  the  same  when  dry,  gaseous  instead  of  qqueous  HCl  wao  used  as 
a cataiysu. 

x£.  Friedlander  jlx,  iO£4. 

13.  Vide  Adams  and  Palmer  ibid. 


. 


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■ 


The  product  thus  obtained  wua  an  extremexy  ligu*,  cottony 
tass,  melting  at  2l8-2lb°."  C.  (corr.  ) { 21i  .0-211° . ‘c , unc  . ) and 
gradually  changing  to  a hard,  brown,  caramel-like  mass  wnen  be  ated 
for  some  time  doiow  its  T.eiting  puxnl  (e.  g.  at  140°)  . It  was  in- 
soluble in  water,  dilute  acias  or  aixalies,  siightxy  soluble  in 
alcohol,  ether,  benzene,  and  ligroin,  ana  very  soluble  in  ‘Chioro- 
ocnzene.  It  thus  resenbled  quite  ciosely  in  all  its  pnysicax 
properties  the  a^axu^ous  coxpound  of  phenyl  arsine  and  oenzaidehyae 
obtained  by  Adams  and  Palmer.  Tne  analytical  data,  nov/ever,  aia 
not  utar  out  this  conclusion  very  cios6iy.  if  this  substances  has 


it  is  evident  that  its  formation  does  not  represent  the  chief 
proauct  when  ultimate  ana  most  stable  conditions  of  equilibrium 
have  been  reached,  in  an  cases  tn.6  chlorobenzene  insoluble 
residue  constituted  at  least  of  the  reaction  product,  ana 

apparently  the  relative  proportion  of  the  latter  proauct  increased 
as  the  reaction  mixture  was  anowed  to  stand  before  extraction  with 
chlorobenzene.  This  residue  was  at  first  a bright  yellow,  sticky 
mass,  smeiiing  strongly  of  benzaiaehyde . On  standing  in  th6  air  it 
gradually  became  lighter  in  color  ana  ary.  After  a coupxe  of 
weeks  it  was  found  to  be  mostly  soluble  in  hot  iO%  NaQH  solution 
although  a dirty,  sticky  residue  remained  insoluble,  un  dilution, 
this  solution  Decame  turbid,  but  no  precipitate  appeared  until  the 
solution  was  made  acid  with  HC1.  The  precipitate  thus  formed  was 
.light  yellow-grey,  and  of  the  consistency  of  molasses.  On  stand- 
ing for  some  time,  it  gradually  became  solid  and  granular.  This 


, t 


N 

I 


precipitate  was  filtered  oil  aim  dissolved  up  xu  y bfi  aioohol,  al- 
most completely  covered  and  anowed  to  evaporate  very  siowiy . 

Alter  three  weeks  it  was  round  that  the  amorphous  yellow  mass  which 
remained  contained  may  clusters  of  tiny,  needlo-iike  crystals. 

These  were  isolated  and  identified  as  p-chioropnenyiarsonic  acid. 
Tne  inference  was  tnat  the  main  product  oi  the  reaction  was  not  the 
condensation  product  expected,  but  p-dichioroarsenobenzene : 


This  accounts  for  tne  changes  above  mentioned,  ior  the  arseno 
compounds  are  usually  yeliow,  and  they  are  all  oxidized  slowly  by 
the  air  to  arsonic  acids.  Attempts  to  isolate  tne  arseno  compound 
failed,  as  would  be  expected  because  these  compounds  are  difficult- 
ly soluble  in  most  reagents,  and  usuany  amorphous,  ana  some  ben- 
zaidehyde  was  present  to  complicate  matters. 

It  was  also  attempted  to  condense  p-chiorophenylarsine  with 
paraldehyde.  The  reaction  was  carried  out  in  the  same  way  as  with 
benzaldehyde . On  the  addition  of  HC1,  the  mixture  became  warm, 
but  remained  liquid.  After  standing  ior  i£  hours  it  was  dissolved 
in  Denzene , dried  with  fused  calcium  chloride , filtered,  and 
fractionated  under  diminished  pressure,  most  of  the  condensation 
product  was  found  to  distill  over,  out  at  the  end  decomposition 
took  pxACe  rather  suddenly,  xeavmg  in  the  flask,  a red,  sticky 
mass.  The  distiixed  product  thus  obtained  was  a colorless  liquid 
boiling  at  i83°  under  £3  mm.  oi  mexcury.  It  was  redistilled.  The 
yield  in  this  case  was  much  better,  amounting  to  about  SOfc  of 
theory.  The  product  nad  a refractive  index  of  l.t>7£6  at  £5°,  and 
a specific  gravity  of  . 74ol.  it  was  insoluble  in  water  and  dilute 


■ 


” — — 77 

HCl,  Dut  soluble  m benzene  ana  chlorobenzene . Analysis  indicated 
the  formula  ^iqH^Q^asCI  which  corresponds  to 

O^sfcHOKCfa/vj* 

Inis  compound  was  very  unstable,  un  standing  it  gradually  under- 
went change  with  th6  separation  of  a soiid  white  materia.  me 
nature  of  this  product  was  not  determined,  cne  amount  obtained  Do- 
ing msuiiicient  lor  analysis.  it  was  insoluble  in  ZQ°/o  HaOH,  even 
after  standing  ior  a xong  time  m tne  air,  and  hence  could  scarcely 
have  represented  an  oxidation  product  oi  the  arsine.  It  was  soxubie 
in  chior obenzene  anu  Ufjon  evaporating  oil  the  solvent  under  dimin- 
ished pressure  at  ordinary  temperatures , no  soxiu  separated  out, 
but  a viscous  xiquid  remained  very  like  the  material  from  which  it 
originally  separated. 

This  investigation  was  extended  to  a study  oi  the  properties 

of  certain  other  arsines.  The  preparation  oi  p-aminophenyiarsme 

i4 

is  described  in  i).  n.  P.  25i,t>7i  . a or  the  present  investigation 

it  was  pxeparea  d/  the  same  metnou  as  tnat  used  m the  preparation 
of  p-chioropnenyiarsme . The  pure  aminophenylarsine  was  axso  iso- 
lated and  condensed  in  the  same  was,  using  three  moles  of  ben- 

J 

zaidehyde  instead  oi  two.  it  was  supposed  that  the  amino  group 
would  iirst  condense  m the  absence  oi  HCi,  and  that  the  arsine 
woura  tnen  react  upon  the  addition  oi  HCi.  This  predict tion  was 
borne  out  by  the  generar  uehavior  of  the  mixture,  un  adding  the 
oenzarden^ae  tile  mixture  became  quite  warm,  and  alter  cooling,  when 
a few  drops  oi  cone.  nCi  had  oeen  added,  the  mixture  neated  up 
again.  The  reaction  mixture  now  gradually  solidified  to  a trans- 
14  Priediander  Al,  1024 . 


. 

' 


Q. 


xucent,  almost  coioness  raad.  It  was  Kept  in  an  atmosphere  of 
CO^  throughout.  After  standing  m carbon  dioxide  for  twelve  hours 
xv,  was  found  that  rea  spots  nad  appeared  ana,  upon  expoexng  tne 
mass  to  tne  axr,  tiie  red  ooior  gradua^y  spread  tnroughout  the 
whole  mass,  henzaidenyde  was  regenerated.  The  mass  u.o'fi  was  founa 
to  be  soluble  m cnxui uucnzene , from  which  solution  it  was  precip- 
itated oy  tne  addition  oi  ailute  aqueous  HC1.  After  filtering  and 
drying,  a rather  heterogeneous  and  very  hara  redaisn  mass  remained 
whicn  was  apparently  compxetery  xixSuxuble  in  any  common  organic 
solvents.  It  was  suspected  of  being: 


tempt  to  hyarolyze  the  compound  with  dilute  HOI  and  thus  to  obtain 
p-diammoarsenobenzene  resulted  in  a decomposition  01  tne  molecule 
with  the  formation  of  black  tarry  material.  Analysis  of  tne  red- 
disn  material  showed  22.26?fe  arsenic.  The  theoretical  value  for  a 
compound  oi  formula  I is  2^.3b?b.  The  disparity  is  probably  due  to 
the  impurity  of  the  matenax.  its  hard,  non-crystaiiine  cnaracter 
and  insoxubixity  made  it  impossible  to  purify. 

XJ-Phenetyiarsine  was  prepared  in  the  same  way  as  p-emuxo- 
ana  p-aminophenyiarsine . Apparently  it  underwent  very  considerable 
decomposition  eitner  during  tne  xeduction  or  during  distillation, 
for  the  product  showed  i4.G4 jo  of  arsenic  instead  of  the  theoi tutox 
value  oi  32. Vo;*.  it  smelled  strongly  of  phene toie  . About  half  of 
ih  K.  H.  P.  206,057 


Since  the  compound 


.LID 

resembles  it  in  color  and  general  solubility  behavior  . An  at- 


' 


■ 


■ 


a gram  oi  the  axaiut)  was  therefore  exposed  to  the  air.  A white 
precipitate  formed  at  once , and  al  ter  standing  lor  several  hours 
an  oil  still  remained.  i'his  was  separated  oy  extracting  tne  suxid 
material  with  a little  ether,  filtering,  and  pulling  off  tne  otnex 
from  tne  filtrate  au  ordinary  temperatures  under  diminished  pres- 
sure. i’he  resraual  on  amounting  to  aoout  u.o  e.  uuc.  identified 
as  ph6netole  by  its  odor  and  boiling  point.  ihe  residual  white 
soiid  amounting  to  about  0.2  g.  was  analyzed  after  drying  at 
60°  for  two  nours.  it  showed  Sl.oo^b  Ox  arsexiic . ihe  theoretical 
value  for  p-pnene tyiarsonic  acid  is  30.4y>  and  for  the  correspond- 
ing arsine  oxide,  55.2>8^fa.  ihe  wnite  powder  was  tnerefore  chieny 

pnene tyxarsomc  aciu,  containing  some  phene tyiarsine  oxide  as  an 

o 

impurity,  it  melted  at  174-6  in  a capnxaiy  m an  oil  Datn  xu 

whicn  the  temperature  was  rapidly  rising,  if,  nowever,  tne  temper- 

o 

ature  rose  slowly,  especially  within  10  of  this  melting  point, 

it  did  not  melt  under  2Vo°.  If  a sample. of  the  material  was  melted 

and  frozen  repeatedly  it  became  infusible,  rhis  behavior  is  char- 

lo 

acteristic  oi  the  aryl  arsonic  acids  , and  is  due  to  tne  xus»  oi 


The  observed  melting  point  is  of  course  of  no  special  signu icance 
except  bo  indicate  tnat  tne  sample  was  not  pure  p-phene tyiarsonic 
acid,  a conclusion  which  is  ooxne  out,  by, the  results  of  the  analysis 
The  product  obtained  by  the  reduction  or  p- pnene tyiarsonic 


a moiecul6  oi  water. 


— > 


16  Morgan,  Organic  compounds  oi  Arsenic  and  Antimony,  p.  74 

17  Ber.  (1908)  41,  18b4 


■ 


. 


10 


acid  thus  undoubtedly  consisted  oi  p-phenetyj.ars±xic  mixed  with 
phenetoie,  the  latter  being  fiomed  by  some  secondary  reaction  tak- 
ing place  during  the  reduction  or  the  steam,  distillation,  and  in- 
volving the  splitting  of  f oi  arsinic  from,  the  ring. 

The  boiling  point  of  the  highest  boiling  fraction  of  the 
mixture  was  162-b0  under  18  mm.  and  this  undoubtedly  represents  the 
boiling  point  of  pure  phene tyiarsine . A rather  remark  ble  iact 
about  this  mixture  is  that  on  oxidation  it  immediately  yields  a 
white  powder.  how  the  arseno  compound  represents  the  first  pos- 
sible stage  in  the  oxidation  of  an  arsine,  and  p-die thoxyarseno- 

IQ 

benzene  is  known  to  be  yellow.  Apparently  the  arseno  compound 
either  was  not  intermediate,  or  it  was  under  these  conditions  ox- 
idized more  rapidly  than  it  was  formed.  This  behavior  is  rather 
unusual,  and  combined  with  the  lability  of  the  AsH2  group  in 
phene tyiarsine , indicates  the  remarkable  and  unexpected  influence 
which  the  OC2H5  group  has  on  the  properties  of  the  phenylarsine 
rest . 


The  mixture  of  phene tyiarsine  and  phenetoie  was  condensed 
with  benzaldehyde  as  follows:  To  14  g.  of  the  mixture,  16  g.  of 

benzaldehyde  was  added  (2  moles  assuming  that  the  phenetylarsine 
is  100$  pure)  and  then  a few  drops  of aqueous  HC1.  Heat  was  evolved, 
and  after  standing  for  12  hours  in  an  atmosphere  of  COg  it  was 
observed  that  crystals  had  separated.  Without  admitting  any  trace 
of  air,  the  mixture  was  now  steam,  distilled  until  nothing  further 
was  carried  over.  About  two  grams  of  a yellow,  sticky  solid  re- 
mained in  the  distilling  liask,  while  in  the  receiver  a considerable 
quantity  of  yellow  oil  had  collected  under  the  water.  It  was 
18  Michaelis.,  Ann.,  320,  300  (1902) 


f 


; 


' 


11. 

separated  off  and  exposed  to  the  air.  .benzaldehyde  and  ohenetoie 
were  obviously  present,  and  later  some  crystals  separated  which 
proved  to  be  phene tylarsonic  acid,  flow  phenetylarsonic  acid  is 
not  volatile,  nor  are  any  of  the  other  possible  oxidation  products 
of  phene tylarsine . it  was .therefore , necessary  to  conclude  that 
th6  arsine  itself  had  distilled  over.  Som.6  of  the  ar3ine  must, 
therefore,  have  remained  unchanged  in  spite  of  the  tact  that  the 
benzaldehyde  was  present  in  large  excess,  or  the  arsine  must  have 
been  regenerated  trom.  its  combination  during  the  distillation.  The 
residue  from  the  steam  distillation  was  now  examined.  it  was  found 
to  be  soluble  in  chlorobenzene,  and  ethyl  alcohol,  irom  which  sol- 
ution on  cooling  there  separated  long,  silky  needles,  which  were 
supposed  to  do  the  condensation  product; 

OCxh6' 

After  recrystallization  and  drying  they  melted  at  220-223°  (corr). 
This  product  amounted  to  less  than  0.1  g.,  and  an  attempt  to  deter- 
mine the  arsenic  content  did  not  yield  a result  of  any  significance. 
The  filtrates  from  both  crystallizations  were  combined  and  the 
solvent  evaporated  off  at  ordinary  temperatures . The  residue  re- 
gaining was  a sticky  viscous,  yellow  liquid.  it  amounted  to  about 
1.5  g.  It  was  supposed  to  contain  some  arseno  compound,  and  som.6 
benzaldehyde  which  nad  been  mechanically  held  back  during  the  dis- 
tillation. 


12 


III.  SIGNIFICANCE  OF  RESULTS 


It  is  evident  that  the  reactions  of  these  arsines  with  ben- 
zaldehyde  are  very  complex,  and  that  in  any  case,  when  equilibrium 
is  reached,  the  product  of  the  type  RAs  (CH0HCgH5)2  represents  but 


a small  fraction  of  the  products  formed.  It  is  possible  to  explain 
the  phenomena  observed  on  the  addition  of  p-chlorophenyl  arsine  to 
benzaldehyde  by  the  reactions  indicated  below. 


The  reaction  goes  practically  quantitatively  at  first  to  the  form- 
ation of  IV  which  is  a white  solid.  At  the  same  time  reaction  B 
sets  in,  but  is  much  slower  than  A.  However,  it  is  more  complete, 
so  that  ultimately  most  of  the  arsine  present  is  changed  into  V. 
This  theory  is  borne  out  by  several  facts,  the  most  important  of 
which  is  the  color  change  above  mentioned.  Benzyl  alchol  was  never 
isolated  from  the  reaction  mixture,  but  Mr.  0»  S.  Palmer  of  this 
laboratory  has  identified  it  as  one  of  the  products  in  the  reaction 
between  phenylarsine  and  benzaldehyde.  In  one  case  alcohol  was 
added  to  the  arsine  before  the  addition  of  benzaldehyde.  Heating 
and  the  formation  of  a solid  took  place  as  usual  on  the  addition 
of  benzaldyhyde,  but  neither  reaction  A nor  B could  have  been  com- 
plete ; since  most  of  the  arsine  was  unchanged  at  the  end  of  an  hour 
and  on  exposing  the  mixture  to  the  air,  much  heat  was  evolved,  and 
p-dichloroarsenobenzene  formed. 

The  reversibility  of  reaction  A must  be  questioned.  Products 


. 


■ ' X 


. 


. 


. 


13 


of  the  type  IV  are  fairly  stable  although,  at  least  in  certain 
cases,  they  decompose  much  below  their  melting  points,  this  de- 
composition being  almost  complete  in  two  hours  at  140°  in  the  case 
of  the  product  IV. 

The  behaviour  of  the  other  two  arsines  studied  furnished 
certain  additional  evidence.  Thus,  in  the  case  of  p-aminopheny- 
larsine  care  was  taken  to  add  just  exactly  the  theoretical  amount 
(3moles)  of  benzaldehyde.  All  the  benzaldehyde  disappeared  after 
the  addition  of  the  HC1,  but  on  exposing  to  the  air,  it  was  at 
least  partially  regenerated.  The  most  rational  explanation  of 
this  behaviour  necessitates  the  assumption  of  a reversible  reaction 
similar  to  the  above: 


(«) 


JU(chOHCuHs)^. 

0 


■f*  C> 


■ ch  syv  O'"-*' 0—0 


is  less  in  evidence  here,  since  in  the  course  of  12  hours  only  a 
few  reddish  spots  had  appeared  in  the  mixture  in  the  absence  of 
air;  but  these  were  sufficiently  obvious  to  justify  the  assumption 


that  some  aldehyde  had  been  reduced,  providing  F is  the  proper 
explanation  for  the  formation  of  the  reddish  product. 


14 


Similar  explanations  suffice  to  account  for  the  observations 
made  in  the  case  of  p-phenetylarsine 


In  this  case  also  reaction  H was  not  so  much  in  evidence,  but 
that  it  actually  took  place  to  some  extent  is  indicated  by  the 
yellow  color  of  the  product  obtained  after  the  completion  of  the 
steam  distillation.  That  is  to  say,  reaction  H was  very  slow,  just 
as  was  reaction  F;  but  that  reaction  G was  reversible  was  indicated 
by  the  fact  that  most  of  the  arsine  originally  present  appeared  in 
the  distillate  from  the  steam  distillation,  in  spite  of  the  fact 
that  a large  excess  of  benzaldehyde  was  present. 

Thus  it  is  concluded  that  compounds  of  the  type  IV,  VIII  and 
X were  formed,  but  that  the  reaction  by  which  they  formed  was  in 
each  case  reversible  so  that  they  were  each  in  equilibrium  with 
the  arsine  from  which  they  are  derived.  In  each  case  the  equilib- 
rium was  displaced  by  the  removal  of  the  arsine  mom  che  field  o^. 
the  reaction;  the  p— chlorophenylansine  was  oxidj.zeo.  by  ohe  benzal— 
dehyde  to  the  corresponding  arseno  compound;  the  p-aminophenylar- 
sine  was  oxidized  on  exposure  to  the  air  to  the  arseno  compound; 
the  p-phenetylarsine  was  removed  by  the  steam. 


A 


15 


The  chief  objection  to  this  explanation  is  that  there  is  no 
direct  evidence  for  the  evolution  of  arsine  from  these  condensa- 
tion products,  and  while  it  is  pointed  out  that  those  compounds 
with  which  this  study  is  concerned  showed  no  very  high  degree  of 
stability,  and  in  certain  cases  (notably  the  compound  of  paralde- 
hyde with  p-chlorophenylarsine ) were  decidedly  unstable;  yet  it 
must  be  admitted  that  the  above  explanations  cannot  be  regarded 
as  completely  consistent  and  satisfactory  unless  they  are  fortified 
with  some  additional  assumptions,  such  as:  that  the  reverse  reac- 
tion is  catalyzed  by  some  substance  which  is  absent  after  the  puri- 
fication, or  that  in  some  manner,  the  purified  product  is  more 
stable  than  that  from  which  it  was  derived.  The  basis  of  these 
speculations  is  made  additionally  insecure  through  the  fact  that 
the  structore  of  these  condensation  products  has  never  been  defi- 
nitely established. 


16 


IV . EX  PER IMENTAL  P ART . 

1.  Preparation  and  properties  of  p-chlorophenylarsonic  acid : This 

substance  has  been  prepared  by  Bertheim18  from  arsanilic  acid  by 

the  Gattemiann  diazo  reaction.  For  the  present  investigation  it 

was  prepared  from  p-chlorooniline  by  a modification  of  the  Bart’s 
19 

reaction  , the  coupling  being  carried  out  in  the  absence  of  free 
20 

alkali  . A typical  run  Is  described  below: 

126  g.  of  p-chloroaniline  was  stirred  up  by  means  of  an  ef- 
ficient mechanical  stirrer  with  600  cc.  HgO  and  180  cc.  cone.  HC1 
(s.  g.  1.19),  cooled  to  0°,  and  diazotized  by  the  addition  of  68  g. 
of  sodium  nitrate  in  250  cc.  of  water,  the  temperature  being  kept 
below  7°.  350  g.  of  crude  ASgO^  (theoretical  plus  80$)  was  dis- 
solved in  1.5  liters  of  water  to  which  565  g.  of  sodium  carbonate 
had  been  added  by  heating  on  the  water  bath  for  two  hours  with  oc- 
casional shaking.  Some  of  this  material  usually  failed  to  go  into 
solution.  The  mixture  was,  therefore,  filtered  with  suction,  and 
to  the  filtrate  10  g.  of  anhydrous  copper  sulphate  was  added  with 
stirring.  The  solution  was  then  cooled  to  approximately  room  tem- 
perature and  the  diazo  solution  siphoned  into  it  very  slowly.  The 
solution  was  stirred  constantly  with  a motor  stirrer  during  this 
addition.  A tendency  to  foam  limits  the  speed  of  the  addition  of 
the  diazo  solution.  It  Is,  therefore,  necessary  to  use  as  large  a 

vessel  as  possible  for  this  reaction,  not  smaller  than  5 liters  

preferably  much  larger.  Foaming  can  often  be  greatly  mitigated  by 
the  addition  of  a few  cc.  of  benzene  occasionally.  Stirring  is 

18.  Ber  (1908)  41,  1854. 

19.  D.  R.  P.  2517  092,  Frdl.,  11,  1030  (1913) 

20.  J.  Ind.  Eng.  Chem.  11,  825"Tl919) 


■ 


. 


, 


t * • 


17 


continued  for  four  hours  after  the  addition  of  the  diazo  solution 
is  complete.  The  mixture  is  then  allowed  to  stand  for  12  hours 
and  filtered  with  suction  from  the  tar.  The  filtrate  is  clear  and 

ciUXU 

slightly  greenish  in  color.  It  is  made/ -with "glacial  acetic.  The 
addition  of  the  acetic  acid  must  be  carried  out  very  carefully, 
since  the  mixture  may  foam  violently.  If  the  approximate  quantity 

of  acid  required  is  known,  the  solution  may  be  added  to  the  acid. 

Pi 

The  foaming  under  these  conditions  is  much  less  . The  purpose  of 
the  addition  of  the  acetic  acid  is  to  precipitate  out  the  excess  of 
ASgO^,  it  having  been  found  experimentally  that  arsenious  acid  is 

2 p 

precipitated  almost  quantitatively  ” from  solutions  of  its  salts  by 
the  addition  of  acetic  acid,  while  p-chlorophenylarsonic  acid  is 
not  so  precipitated.  If  the  As^O,,  thus  precipitated  is  now  filter- 
ed off,  the  filtrate  will  be  found  to  be  perfectly  clear,  and  on 
the  addition  of  cone.  HC1  (about  one-fourth  the  total  volume)  the 

21.  J.  Am.  Chem.  Soc.  43,  161  (1912) 

22.  That  is,  for  the  purposes  under  consideration.  The  solubility 

of  AsgOg  in  water  approaches  20  g.  per  liter  at  ordinary  tempera- 
tures. HAsOp  is,  however,  ionized  in  0.1N  solution  very  slightly 

between  0.002  and  0.008%  according  to  A.  A.  Noyes,  Qualitative  Chem- 
ical Analysis,  p.  125.  Acetic  acid  in  similar  concentrations  is 
ionized  to  the  extent  of  1«2%.  Hence,  in  a solution  of  AsgO*  con- 
taining acetic  acid,  the  concentration  of  AsOg  will  be  very  low, — - 
probably  of  the  order  of  .0001  equivalents  per  liter  (mass  action 
effect).  Any  further  repression  of  the  ionization  of  HAsOg  by  an  in- 
crease of  the  hydrogen  ion  concentration  (addition  of  HC1)  will, 
therefore,  of  necessity  be  extremely  slight;  and  hence  will  have  very 
little  effect  on  the  total  concentration  of  HAsOg.  H-AsO^  is  a much 
stronger  acid  than  HAsOp  (Ionization  20-45%)  and  p-chlorophenylar- 
sonic  acid  would  be  predicted  to  be  of  the  same  order,  and  its  solu- 
bility in  water  should  be  quite  appreciable  (cf.  phenylarsonic  acid). 
Acetic  acid  in  the  presence  of  large  quantities  of  sodium  acetate 
which  are  present  does  not  furnish  a sufficiently  high  concentration 
of  hydrogen  ions  to  exceed  the  solubility  product  of  p-chlorophenyl- 
arsonic  acid,  but  HC1  does;  and,  moreover,  the  salting  out  effect  of 
a moderately  concentrated  solution  of  HC1  on  the  neutral  molecules 
should  be  much  greater  than  that  of  HC1  on  the  neutral  molecules  of 
HAsOp,  a very  weak  electrolyte.  See  Washburn,  Principles  of 
Physical  Chemistry  1915,  pp.  227,  228. 


* 

, 


. 


. 


. 


. 

. 


■ 


* 


» in' 


18 


p-chlorophenylarsonic  acid  will  be  precipitated  as  a perfectly 
white,  granular  precipitate.  It  is  filtered  off  with  suction,  and 
thoroughly  washed  with  cold  water  to  remove  any  traces  of  salt,  and 
dried  for  several  days  by  exposure  to  the  air.  The  product  is  a 
fine,  white  tasteless,  dusty  powder.  The  yield  amounts  to  about 
200  g.  or  85$  of  theory.  Its  solubility  behavior  is  indicated  below: 
Solvent  Hot  Cold 


Water 

Dilute  alkalies 

Cone  HC1 

Alcohol 

Ethyl  acetate 

Glacial  acetic  acid 

Ether 


Somewhat 
Very  soluble 
Very  soluble 
Very  soluble 
Soluble 
Quite  soluble 
Somewhat  soluble 


Sparingly 
Very  soluble 
Insoluble 
Sparingly 
Somewhat  soluble 
Soluble 

Somewhat  soluble 


In  a capillary  tube  a sample  of  the  crude  acid  did  not  melt, 
but  decomposed  at  about  320°.  Similarly  a sample  recrystallized 
from  alcohol  decomposed  at  348°.  It  crystallized  in  needles  from 


alcohol,  glacial,  acetic,  or  hot  concentrated  HCl.  The  latter  is 
an  ideal  solvent  so  far  as  solubility  behavior  is  concerned,  and 
moreover,  boiling  with  HCl  would  probably  distill  off  as  AsClg  any 
traces  of  AsgOg  which  might  be  present;  but  analysis  of  samples  re- 
crystallized from  this  solvent  always  showed  too  high  a chlorine 


content,  hov/soever  thoroughly  they  were  washed  with  boiling  water. 
The  sample  used  in  obtaining  the  following  analytical  data  was  crys- 
tallized once  from  glacial  acetic  and  twice  from  95$  ethyl  alcohol 
and  dried  to  constant  weight  at  90°  under  diminished  pressure. 


.1612  g.  sample  used  26.38  cc.  I2  sol.  =-31.58$  As 

.1782  g.  sample  used  28.77  cc.  Ig  sol.  - 31.89$ 

.1966  g.  sample  used  31.60  cc.  Ip  sol.  = 31.74$ 

1 cc.  sol  = .001975  g.  As  Average  31.74$ 

.4190  g.  sample  gave  .2539  g.  AgCl  z 14.99$  Cl 

.5190  g.  sample  gave  .3176  g.  AgCl  =-15.14$  Cl 

Average  = 15.06 

Calculated  for  C6H603C1As:  As,  31.71$;  Cl,  15.01$. 


19 


9^ 

The  arsenic  was  determined  by  the  method  of  Ewins  and  the  chlor 
ine  by  the  method  of  Carius. 


i 


i 


23  Chem.  Soc.  Trans.  (1916)  109,  1356. 


' 


. 


20 


2.  Preparation  and  properties  of  p-chlorophenylarsine • Consider- 
able difficulty  was  experienced  in  working  out  the  proper  conditions 
for  the  reduction  of  p-chlorophenylar sonic  acid.  The  method  finally 
adopted  was  as  follows:  70  g.  of  p-chlorophenylar sonic  acid  and 

350  g.  of  thoroughly  amalgamated  zinc  dust  were  placed  in  a 3 liter 
round  bottom  flask,  and  250  cc.  of  methyl  alcohol  added.  The  flask 
was  provided  with  a two  hole  rubber  stopper.  Through  one  of  these 
holes  extended  the  lower  end  of  a long  glass  condenser,  the  upper 
end  being  provided  with  a mercury  trap  consisting  of  a bent  glass 
tube  dipping  into  a tube  of  mercury.  The  other  hole  of  the  stopper 
carried  a 3mm.  glass  tube  about  two  decimeters  long,  and  connected 
at  the  upper  end  with  a 500  cc,  dropping  funnel.  All  joints  were 
sealed  with  paraffin.  The  dropping  funnel  was  filled  with  cone. 

HC1,  the  long  tube  filled  with  the  acid  and  the  stop-cock  so  reg- 
ulated that  the  acid  dropped  in  at  the  rate  of  about  3 or  4 drops 
to  the  minute.  The  combined  effects  of  capillarity  and  the  pressure 
inside  the  flask  prevented  the  long  tube  from  emptying  even  if  the 
acid  should  all  run  out  of  the  funnel  during  the  night.  About  a 
liter  of  cone.  HC1  was  thus  added,  and  the  run  was  considered  com- 
plete when  the  zinc  had  all  or  practically  all  disappeared.  This 
usually  required  from  three  days  to  one  week.  The  stopper  was  now 
removed  from  the  flask  and  quickly  replaced  by  another  bearing  three 

glass  tubes, one  connected  to  a source  of  steam,  another  to  a 

source  of  COg,  and  another  to  a condenser.  The  whole  set-up  is 
illustrated  in  the  following  diagram: 


' 


. 

. 


■ 

. 


. 

21 


Before  admitting  steam  the  apparatus  was  permitted  to  fill  complete- 
ly with  COg.  Steam  was  then  passed  through  for  about  four  hours. 

The  arsine  solidified  from  time  to  time  in  the  condenser,  and  was 
pushed  out  by  shutting  off  the  condenser  water  and  blowing  out  with 
COg.  When  the  distillation  was  complete,  the  stopper  bearing  the 
adaptor  was  removed  and  immediately  replaced  by  one  bearing  a right- 
angled  tube  attached  to  a source  of  COg.  The  suction  flask  was  now 
removed  from  its  ice  bath.  The  p-chlorophenylarsine  was  found  col- 
lected as  dark  solid  at  the  bottom  of  the  flask.  A little  glass 
wool  was  stuffed  into  the  tubulure  of  the  suction  flask,  the  flask 
tipped,  and  the  water  pushed  through  the  tubulure  by  the  entrant 
steam  of  CO p.  The  stopper  was  partially  removed  without,  however, 
removing  the  end  of  the  COg  tube  and  200  cc.  of  ether  added.  The 
tubulure  of  the  suction  flask  was  inserted  into  the  mouth  of  a 
500  cc.  separatory  funnel  filled  with  CO2  and  the  etheral  solution 
poured  out.  The  flask  was  washed  with  a little  ether  and  the  pro- 
cess repeated.  Water  was  drawn  off  from  the  bottom  of  the  funnel 


• 

' 

- 

. 

. 


and  then  solid  KOH  and  fused  CaC12  were  added  to  the  solution,  and 
it  was  allowed  to  dry  for  two  hours.  The  method  of  transferring  the 
ethereal  solution  to  the  distilling  flask  was  as  follows:  The 

Claissen  flask  was  provided  with  a stopper  hearing  two  tubes,  one 

it 

a capillary  for  CO  (as  in  a Bruhl  apparatus),  and  the  other  bent 
twice  at  right  angles  and  closed  at  the  lower  end  with  a piece  of 
stoppered  gum  tubing.  Dry  COg  was  admitted  through  the  capillary 
from  mercury  trap  so  arranged  as  to  provide  the  gas  at  a constant 
pressure  slightly  greater  than  atmospheric.  The  Claissen  flask 
was  connected  with  a receiver  consisting  of  an  ordinary  distilling 
bulb,  and  the  latter  with  an  air  pump  and  a manometer  as  in  an  or- 
dinary vacuum  distillation.  After  the  system  had  been  alternately 
evacuated  to  the  limits  of  the  pump  and  filled  four  times  with  COg 
at  the  pressure  of  the  source,  the  stopper  was  pulled  off  from  the 
right-angled  tube  and  the  latter  dipped  into  the  ethereal  solution, 
CO2  being  continuously  admitted.  The  COg  was  then  shut  off  and  the 
suction  turned  on,  and  the  flask  filled  with  ether.  The  suction 
was  so  regulated  as  not  to  draw  in  any  air,  and  as  soon  as  the  de- 
sired amount  of  ether  was  drawn  in  the  suction  was  shut  off  and  the 
COg  turned  on.  The  separatory  funnel  was  then  withdrawn  and  stop- 
pered, the  right-angled  tube  closed,  the  ether  pulled  off  in  vacuo, 
and  the  process  repeated  until  all  the  solution  had  been  transferred 
to  the  flask.  The  solution  was  then  fractionated.  No  special  re- 
ceiving flask  was  necessary,  providing  that  the  whole  system  was 
filled  with  COg  before  changing  receivers.  Considerable  experience 
taught  that  the  best  method  of  ensuring  complete  exclusion  of  air 
from  the  final  product  was  as  follows: 


. 

. 


23 


When  distillation  was  complete,  the  suction  was  cut  off  and  the 
system  filled  with  COg  the  stop-cock  to  the  source  being  left  open. 
When  the  rubber  suction  tube  was  now  pulled  from  the  glass  delivery 
tube  of  the  receiving  flask,  a stream  of  COg  rushed  out  of  that  tube 
and  effectively  prevented  the  ingress  of  any  air.  The  rubber  suction 
tube  was  then  replaced  by  a rubber  tube  through  which  a stream  of 
COg  poured,  and  the  receiver  drawn  off  from  the  delivery  tube  of  the 
distilling  flask.  No  air  could  enter  the  top  of  this  flask  because 
COg  was  passing  continuously  out;  and  hence  it  was  not  necessary  to 
stopper  the  flask  until  the  COg  was  cut  off.  This  arrangement  made 
it  possible  to  draw  out  samples,  etc.  without  any  danger  of  contamin- 
ation from  the  air.  The  optimum  yield  of  twice  redistilled  product 
was  about  26  g. 

Several  other  methods  for  reducing  the  arsonic  acid  were  tried 
without  success.  The  presence  of  the  methyl  alcohol  seems  to  be  ab- 
solutely essential,  probably  because  the  solubility  of  the  arsonic 
acid  in  water  is  not  great.  Some  traces  of  arsine  as  indicated  by 
the  odor  were  always  formed  in  reductions  carried  out  without  the  use 
of  methyl  alcohol,  but  no  arsine  could  be  isolated.  Attempted  re- 
ductions using  zinc  dust  and  solid  NaOH  also  failed.  Ether  extrac- 
tion methods  also  were  unsuccessful,  supposedly  because  no  consider- 
able reduction  took  place  unless  methyl  alcohol  was  present,  and  in 
its  presence  the  ether  extraction  method  is  complicated  by  the  con- 
siderable solubility  of  ether  in  the  alcohol  water  mixture. 

p-chlorophenylarsine  which  has  been  twice  redistilled  is  a solid 
crystallizing  in  very  thin,  flat,  perfectly  transparent  leaves. 

These  crystals  often  attain  a size  of  1.5  cm.  square,  and  in  the  re- 
duction of  the  arsonic  acid  where  some  of  the  arsine  vapor  is  carried 


24. 

up  out  of  the  surface  of  the  liquid,  they  condense  against  the  sides 
of  the  flasks,  standing  out  at  right  angles  to  its  surface. 

The  odor  is  characteristic  and  persistent.  It  is  not  unpleas- 
and,  and  resembles  benzene  to  some  extent. 

The  observed  boiling  points  at  various  pressures  are  recorded 
below. 

Pressure  Temperature 


18-20  mm. 

98-101° 

33 

116 

38 

119 

67 

•143-6 

200 

159 

It  melts  at  30.5-30.7°.  It  is  soluble  in  ether  and  alcohol, 
but  insoluble  in  water.  On  exposure  to  the  air  it  is  immediately 
oxidized  to  the  yellow  arseno  compound  with  the  evolution  of  heat. 

Analysis  of  the  arsine  was  carried  out  as  follows: 

Small  bulbs  resembling  Victor  Meyer  bulbs  were  blown  on  long,  thin 
capillaries.  The  bulb  was  weighed,  heated  in  a flame,  and  the  tip 
quickly  dropped  into  the  molten  arsine.  On  cooling,  a drop  of  the 
arsine  sucked  back  into  the  bulb.  This  was  carefully  heated  to  boil- 
ing and  the  bulb  again  cooled.  The  bulb  no?/  filled  with  the  arsine. 
The  capillary  was  drawn  rapidly  through  a flame  to  expell  the  arsine 
in  it,  and  the  tip  sealed  off.  It  was  then  weighed.  For  the  deter- 
mination of  arsenic  the  capillary  was  broken  off  and  the  broken 
peices  together  with  the  bulb  wrapped  up  in  a peice  of  filter  paper, 
the  bulb  smashed  with  a hammer,  and  the  package  dropped  into  a 500  cc 
Kjeldahl.  The  proceedure  from  here  on  was  simply  the  method  of 
Ewins,  the  addition  of  starch  being  omitted.  Chlorine  was  determined 
by  the  method  of  Carius.  The  bulb  was  placed  in  the  digestion  tube 
and  broken  by  dropping  in  a heavy  glass  slug.  The  arsine  was  then 


. 


- 

, 


; v 


25 


allowed  to  oxidize  in  the  air,  and  the  nitric  acid  added  very  care- 
fully a drop  at  a time  and  with  careful  cooling,  since  nitric  acid 
sometimes  reacts  with  explosive  with  the  arseno  compound.  After  the 
tube  was  opened,  the  silver  chloride  was  dissolved  out  with  ammonia, 
filtered  from  the  glass,  and  reprecipitated  with  HNO3 . It  was,  of 
course,  necessary  to  digest  the  reprecipitated  AgCl  for  several  hours 
in  the  dark  to  obtain  a filterable  precipitate.  Some  of  the  silver 
chloride  usually  remained  stuck  in  the  peices  of  capillary  and  did 
not  dissolve  in  ammonia.  It  was  necessary  to  shake  the  tube  until 
these  capillaries  were  completely  broken  up  against  the  glass  slug. 

.5147  g.  sample  required  103.64  cc.  Ig  sol.  39.75$  As 
.3622  g.  72.20  cc.  39.37 

1 cc.  ig  sol.  = .001975  g.  as  Average  39.51 

.4259  g.  sample  gave  .3184  g.  AgCl  18.50$  Cl 

.4592  g.  .3520  g.  18.97 

.2539  .1914  18.65 

Average  18.71 


Calculated  for  CgH4AsCl:  Cl,  18.81$;  As,  39.79$ 


' , 

• 

« 

* 

. 

• 

• 

* 

• 

• 

• 

- 

26 


3 . p-chlorophenylarsine  benzaldehyde  condensation  product; 
The  preparation  of  this  compound  and  its  properties  is 
in  the  descriptive  part  of  this  paper. 

Analytical  data: 

.1406  g.  sample  gave  .0473  g.  AgCl  = 8.32$  Cl 

.1676  g.  .0558  g.  " = 8.23$ 

.1082  g.  required  8.95  cc.  Ig  sol.  16.34$ 

.1144  g.  required  9.21  cc.  Ig  sol.  15.90$ 

1 cc.  i.2  sol  = .001975  g.  As 

Calculated  for  CgOHqQOgClAs : As,  18.63$;  Cl,  8.74$ 


analysis . 
described 


. 


. 

. 


27 


4.  p-chlorophenylarsine  paraddehyde  condensation  product;  Analysis. 

The  preparation  and  properties  of  this  compound  are  described 
in  the  descriptive  part  of  this  paper. 

Analytical  data: 

.3215  g.  sample  gave  .1620  g.  AgCl  = 12.47$  Cl 

.3601  g.  .1820  g.  , 12.50$ 

Average  12.49$ 

.3674  g.  sample  required  50.01  cc.  Iq  sol.  26.88$  As 

.3771  g.  52.18  cc.  27.33$ 

1 cc  Ig  sol  = .001975  g.  As  Average  27.11$ 

Calculated  for  C10H14  02  As  Cl:  Cl,  12.82$;  As,  27.12$. 


. 

. ' 


. 


. 


* 


. 


- 


28 


5.  Preparation  of  arsanilic  acid  and  its  reduction:  Arsanilic  acid 

was  first  prepared  by  Bechamp  in  18632^  by  heating  aniline  arsenate 
to  190-200°.  This  method  i3  apparently  the  only  one  which  has  been 
used  in  preparing  this  important  arsonic  acid.  The  latest  modifica- 
tion of  this  method  is  that  of  Cheetham  and  Schmidt'^ 'J , who  claim 
20$  yields  when  working  with  small  quantities.  The  modified  Bart's 
reaction  had  been  found  in  this  laboratory  to  work  so  smoothly  in 
the  preparation  of  many  arsonic  acids  that  it  was  thought  worth  while 
to  work  out  the  conditions  for  the  preparation  of  p-acet7/larsanilic 
acid  by  this  reaction  and  for  its  subsequent  hydrolysis  to  arsanilic 
acid.  The  preparation  of  acetylarsanilic  acid  by  Bart's  reaction  is 

O 

described  in  D.  R.  P.  250,264AvU.  The  proceedure  used  in  the  present 
investigations  was  as  follows: 

50  g.  of  pure  (Eastman)  p-aminoacete.nilide  in  200  cc.  HgO  and 
100  cc.  EC1  (£.g.  1.19)  was  diazotized  with  23  g.  of  solution  of 
NaN02  in  500  cc,  HgO.  120  g.  AsgO^  and  200  g.  NagCOg  were  dissolved 
in  350  cc.  H2O  with  heating,  filtered,  and  to  the  filtrate  3 g. 

GuSO^  was  added.  To  this  cooled  solution  the  diazo  solution  was 
added  with  stirring,  the  mixture  made  acid  with  acetic  acid,  filter- 
ed, and  the  filtrate  treated  ?;ith  an  excess  of  HC1.  65  g.  of 

p-acetylaminoarsonic  acid  was  obtained 75$  of  theory.  HCl>  NaOH, 

and  HgSO^  in  various  concentrations  were  tried  as  hydrolytic  agents. 
NaOH  was  found  to  give  the  best  results  and  to  permit  the  isolation 
of  the  arsanilic  acid  most  readily.  The  proceedure  was  as  follows: 

24  Compt.  rend.  56,  I,  1172  (1865)  Abs.  in  Jahrsbericht  (L.  & K. ) 

(I860)  414. 

25  J.  Am.  Chem.  Soc.  42,  828,  (1920) 

26  Friedlander  VIII,  T£25 


* 

■ 

’ 

, 

• * * 

. 

• 

• 

. 

. 


- 

. 


29 


6,5  g.  |>-acetylaminoarsonic  acid  was  boiled  under  reflux  for  2 hours 
with  35  cc.  of  20$  NaOH  solution.  The  mixture  was  then  boiled  ten 
minutes  with  a little  animal  charcoal,  and  filtered  into  50  cc,  of 
95$  ethyl  alcohol.  The  resulting  solution  was  cooled  with  ice  and 
10  cc.  of  40$  acetic  acid  added.  Crystals  separated  out  after  a 
short  time  until  the  mass  was  nearly  solid.  30  cc  more  of  alcohol 
was  then  added  and  the  mixture  allowed  to  stand  over  night.  The 
sodium  salt  was  then  filtered  off,  and  washed  with  alcohol  and  ether. 
Yield,  3.6  g.  or  60$  of  theory.  With  a little  experimentation  the 
yields  of  this  product  (calculated  on  the  acetylarsanilic  acid) 
should  undoubtedly  be  run  up  to  very  nearly  100$.  The  amount  of 
sodium  hydroxide  solution  used  in  this  experiment  was  probably  ex- 
cessive. Using  smaller  relative  amounts  of  sodium  hydroxide  solu- 
tion and  working  with  larger  quantities  this  would  undoubtedly  be 
an  entirely  practicable  method  for  the  preparation  of  arsanilic  acid. 

The  process  would  also  be  much  simplified  if  the  free  acid  were  pre- 
fab nyarogen  ion  conctentx'tit-Lon  instead  of  isolating  pr. 

cipitated  out  by  properly  adjusting  theAsodium  salt  with  alcohol. 

In  the  hydrolysis  it  is  quite  essential  that  the  acid  or  alkaline 
hydrolytic  agent  be  not  too  dilute,  since  arsanilic  acid  is  decom- 
posed by  hot  water  rather  rapidly.  In  the  presence  of  fairly  con- 

2ft 

eentrated  acids  or  alkalies,  it  is,  however,  perfectly  stable. 

Reduction  of  arsanilic  acid:  This  reduction  was  carried  out 

precisely  as  in  the  case  of  p-chlorophenylarsonic  acid,  the  propor- 
tions being  the  same.  It  was,  of  course,  necessary  to  make  the  re- 
action mixture  alkaline  before  steam  distilling.  It  distills  much 
more  slowly  than  does  the  chlorophenylarsine.  The  yield  of  twice  re- 
distilled product  from  100  g.  of  arsanilic  acid  was  24  g. 

27  Sec  J.  Am.  Chem.  Soc.  42,  828,  (1920) 

28  E.  Schmitz,  Ber.,  (191T7  47,  365;  ibid  996 


. 


. 


. 

. 

. 

. 

* 

«* 

. 

, 

, 

" 


• : 


, 

. 

. 

. 

. 

• 

30 


The  product  was  a colorless  liquid  boiling  at  145-7° 

sure  of  41  mm.  This  agrees  with  the  description  of 

oq 

arsine  in  D.  R.  P.  251,  571. 


under  a pres- 
p-aminophenyl- 


29  Friedlander,  XI,  1024. 


. 

♦ • . *v 


31 


6.  Preparation  of  p-phenolarsonic  acid  and  its  reduction:  The 

method  used  was  that  of  Jacobs  and  Heidelberger  . Yields  of  crude 
product  were  approximately  20 %,  but  considerably  less  than  this  when 
calculated  against  the  recrystallized  product.  Contrary  to  the 
statements  of  Jacobs  and  Heidelberger,  tar  was  always  formed,  and  the 
crude  sodium  salt  was  always  colored.  This  color  was  removed  by  a 
single  precipitation  from  a concentrated  aqueous  solution  by  alcohol. 

Syrupy  arsenic  acid  was  prepared  from  crude  arsenic  trioxide 
according  to  the  method  of  Vannino  (3±  ).  In  dealing  with  quantities 
of  over  100  g.  it  is  quite  important  to  carry  the  reaction  out  in  a 
large  dish  (not  in  a flask,  or  as  Vannino  recommends,  in  a retort) 
and  to  add  the  ASgO^  to  the  acid. 

The  method  used  by  Jacobs  and  Heidelberger  in  isolating  the 
product  is  very  tedious  and  attempts  were  made  to  simplify  it.  The 
magnesium  salt  was  isolated  in  two  runs  instead  of  the  sodium  salt. 
This  was  carried  out  as  follows: 

The  reaction  was  run  as  usual,  using  450  g.  arsenic  acid  and 
200  g.  phenol,  heating  at  150°  for  6 hours,  and  extracting  the  pro- 
duct with  two  liter  of  HgO.  This  filtered  extract  was  divided  into 
two  equal  fractions.  The  sodium  salt  was  isolated  from  the  first  by 
neutralizing  with  Ba(0H)g,  exactly  removing  the  excess  barium  ions 
with  H2S0A,  filtering,  exaporating  in  vacuo,  exactly  neutralizing 
with  NaOH,  evaporating  in  vacuo  until  crystallization  began,  adding 
a large  excess  of  alcohol,  cooling  for  12  hours,  and  filtering  off 
the  sodium  salt.  The  second  fraction  was  treated  as  follows:  250  g. 
ice,  300  g.  MgCl2,  200  g.  NH^Cl,  and  100  cc.  excess  cone.  NH^OH,  and 

were  added  and  the  mixture  allowed  to  stand  for  several  hours. 

30  J.  Am.  Ghem.  Soc.  (1914)  41,  1446. 

31  Handbuck  der  ?rapMrativen  Chemie  I,  184  


- 


' 


. 


. 


. 

. 

[tout  n 

. 


. 

. 


. 


* 


32. 


It  was  then  filtered.  The  filtrate  was  heated  to  boiling,  whereupon 
the  magnesium  salt  of  the  p-phenolarsonic  acid  separated.  A compar- 
ison of  the  yields  from  the  two  fractions  is  shown  below: 

Run  III  Run  IV 

Mg  salt  30  g.  49  g. 

Na  salt  62  g.  57  g. 

The  isolation  of  the  magnesium  salt  is  extremely  simple  compar- 
ed with  the  isolation  of  the  sodium  salt,  but  the  magnesium  salt  13 
not  so  clean  a product  and  the  yields  are  not  so  good.  It  is  proba-- 
Difi  that  further  experimentation  would  improve  both  factors  and  make 
this  process  entirely  practicable. 

The  effect  of  the  use  of  an  excess  of  phenol,  instead  of  an  ex- 
cess of  the  arsenic  acid  was  tried  in  one  experiment.  The  excess 
phenol  was  removed  by  distillation  in  vacuo.  A dirty  gum  was  formed 
from  which  no  crystalline  product  could  be  isolated. 

Preparation  of  p-hydroxyphenylarsine : p-phenolarsonic  acid  was 

reduced  by  the  same  method  used  in  preparing  p-chlorophenylar sonic 
acid  excepting  that  the  methyl  alcohol  was  omitted,  p-phenolarsonic 
acid  being  extremely  soluble  in  water.  The  reaction  mixture  was 
steam  distilled.  The  distillate  contained  only  water.  The  contents 
of  the  reduction  flask  were  then  extracted  with  ether.  The  extract 
was  black,  the  black  material  supposedly  coming  from  the  zinc.  It 
was  extracted  with  10$  NaOH.  The  NaOH  extract  was  black.  It  was 
saturated  with  COg,  and  extracted  with  ether.  The  ethereal  solution 
was  now  colorless.  It  was  again  extracted  with  10$  NaOH  and  the  ex- 
tract saturated  with  COg.  A buff  colored  precipitate  was  formed, 
apparently  the  p-dihydroxyarsenobenzene.  If  HCl  was  used  instead  of 
COg  as  a precipitant,  the  precipitate  was  red.  All  the  reactions 
were  carried  out  in  an  atmosphere  of  CO2.  p-hydroxyphenylarsine  is 


. 


- 


. 

. 


, 

53 


2. 


32 

described  in  D.  R.  P.  251,  571  as  a white  powder  which  readily 
decomposes  on  heating  or  exposure  to  the  air.  Apparently  it  was  not 
formed  in  the  present  case;  or  else  decomposed  during  the  attempt 

to  isolate  it. 


I 


32  Friedlander  XI,  1042 


ii 


« . . 


I « 


34. 


7.  Preparation  of  p-phenetylarsonic  acid  and  its  reduction;  This 
acid  was  prepared  in  excellent  yields  from  p-phenetidine  by  the  mod- 
ified  Bart’s  reaction  • It  was  reduced  in  the  same  way  as  the  other 
arsonic  acids  described  above,  and  the  arsine  isolated  in  the  same 
way.  The  properties  of  the  arsine  are  described  in  the  descriptive 
part  of  this  paper. 


33  This  preparation  was  carried  out  by  Mr.  (J.  H.  Cheney  of  this 
laboratory. 


4 

" 


35 


IV.  SUMMARY . 

1.  The  preparation  of  p-chlorophenylarsine,  p-aminophenylarsine, 
and  p-phenetylarsine  is  described.  Of  these  p-chloropnenyl-  and 
p-phenetyl -arsine  are  new. 

2.  The  reactions  of  these  arsines  with  certain  aldehydes  have  been 
studied. 

3.  The  preparation  of  p-chlorophenylarsonic  acid  and  of  arsanilic 
acid  by  the  modified  Baht’s  reaction  is  described. 


. 


- 


, 

* 


36 


V.  ACKNOWLEDGEMENT. 

This  problem  was  suggested  by  Professor  Roger  Adams  and  the 
experimental  work  was  done  under  his  direction.  The  writer  ex- 
presses his  appreciation  of  the  kindly  interest  and  guidance  which 
Professor  Adams  offered,  and  without  which  this  investigation  would 
have  been  impossible. 


